block: move cmdfilter from gendisk to request_queue

cmd_filter works only for the block layer SG_IO with SCSI block
devices. It breaks scsi/sg.c, bsg, and the block layer SG_IO with SCSI
character devices (such as st). We hit a kernel crash with them.

The problem is that cmd_filter code accesses to gendisk (having struct
blk_scsi_cmd_filter) via inode->i_bdev->bd_disk. It works for only
SCSI block device files. With character device files, inode->i_bdev
leads you to struct cdev. inode->i_bdev->bd_disk->blk_scsi_cmd_filter
isn't safe.

SCSI ULDs don't expose gendisk; they keep it private. bsg needs to be
independent on any protocols. We shouldn't change ULDs to expose their
gendisk.

This patch moves struct blk_scsi_cmd_filter from gendisk to
request_queue, a common object, which eveyone can access to.

The user interface doesn't change; users can change the filters via
/sys/block/. gendisk has a pointer to request_queue so the cmd_filter
code accesses to struct blk_scsi_cmd_filter.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 11 insertions, 33 deletions

diff --git a/block/bsg.c b/block/bsg.c
index 5a68b09..0aae8d7 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -45,8 +45,6 @@ struct bsg_device {
 	char name[BUS_ID_SIZE];
 	int max_queue;
 	unsigned long flags;
-	struct blk_scsi_cmd_filter *cmd_filter;
-	mode_t *f_mode;
 };
 
 enum {
@@ -174,7 +172,8 @@ unlock:
 }
 
 static int blk_fill_sgv4_hdr_rq(struct request_queue *q, struct request *rq,
-				struct sg_io_v4 *hdr, struct bsg_device *bd)
+				struct sg_io_v4 *hdr, struct bsg_device *bd,
+				int has_write_perm)
 {
 	if (hdr->request_len > BLK_MAX_CDB) {
 		rq->cmd = kzalloc(hdr->request_len, GFP_KERNEL);
@@ -187,8 +186,7 @@ static int blk_fill_sgv4_hdr_rq(struct request_queue *q, struct request *rq,
 		return -EFAULT;
 
 	if (hdr->subprotocol == BSG_SUB_PROTOCOL_SCSI_CMD) {
-		if (blk_cmd_filter_verify_command(bd->cmd_filter, rq->cmd,
-						 bd->f_mode))
+		if (blk_verify_command(&q->cmd_filter, rq->cmd, has_write_perm))
 			return -EPERM;
 	} else if (!capable(CAP_SYS_RAWIO))
 		return -EPERM;
@@ -244,7 +242,7 @@ bsg_validate_sgv4_hdr(struct request_queue *q, struct sg_io_v4 *hdr, int *rw)
  * map sg_io_v4 to a request.
  */
 static struct request *
-bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr)
+bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, int has_write_perm)
 {
 	struct request_queue *q = bd->queue;
 	struct request *rq, *next_rq = NULL;
@@ -266,7 +264,7 @@ bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr)
 	rq = blk_get_request(q, rw, GFP_KERNEL);
 	if (!rq)
 		return ERR_PTR(-ENOMEM);
-	ret = blk_fill_sgv4_hdr_rq(q, rq, hdr, bd);
+	ret = blk_fill_sgv4_hdr_rq(q, rq, hdr, bd, has_write_perm);
 	if (ret)
 		goto out;
 
@@ -568,25 +566,6 @@ static inline void bsg_set_block(struct bsg_device *bd, struct file *file)
 		set_bit(BSG_F_BLOCK, &bd->flags);
 }
 
-static void bsg_set_cmd_filter(struct bsg_device *bd,
-			   struct file *file)
-{
-	struct inode *inode;
-	struct gendisk *disk;
-
-	if (!file)
-		return;
-
-	inode = file->f_dentry->d_inode;
-	if (!inode)
-		return;
-
-	disk = inode->i_bdev->bd_disk;
-
-	bd->cmd_filter = &disk->cmd_filter;
-	bd->f_mode = &file->f_mode;
-}
-
 /*
  * Check if the error is a "real" error that we should return.
  */
@@ -608,7 +587,6 @@ bsg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 	dprintk("%s: read %Zd bytes\n", bd->name, count);
 
 	bsg_set_block(bd, file);
-	bsg_set_cmd_filter(bd, file);
 
 	bytes_read = 0;
 	ret = __bsg_read(buf, count, bd, NULL, &bytes_read);
@@ -621,7 +599,7 @@ bsg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 }
 
 static int __bsg_write(struct bsg_device *bd, const char __user *buf,
-		       size_t count, ssize_t *bytes_written)
+		       size_t count, ssize_t *bytes_written, int has_write_perm)
 {
 	struct bsg_command *bc;
 	struct request *rq;
@@ -652,7 +630,7 @@ static int __bsg_write(struct bsg_device *bd, const char __user *buf,
 		/*
 		 * get a request, fill in the blanks, and add to request queue
 		 */
-		rq = bsg_map_hdr(bd, &bc->hdr);
+		rq = bsg_map_hdr(bd, &bc->hdr, has_write_perm);
 		if (IS_ERR(rq)) {
 			ret = PTR_ERR(rq);
 			rq = NULL;
@@ -683,10 +661,11 @@ bsg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 	dprintk("%s: write %Zd bytes\n", bd->name, count);
 
 	bsg_set_block(bd, file);
-	bsg_set_cmd_filter(bd, file);
 
 	bytes_written = 0;
-	ret = __bsg_write(bd, buf, count, &bytes_written);
+	ret = __bsg_write(bd, buf, count, &bytes_written,
+			  file->f_mode & FMODE_WRITE);
+
 	*ppos = bytes_written;
 
 	/*
@@ -792,7 +771,6 @@ static struct bsg_device *bsg_add_device(struct inode *inode,
 	bd->queue = rq;
 
 	bsg_set_block(bd, file);
-	bsg_set_cmd_filter(bd, file);
 
 	atomic_set(&bd->ref_count, 1);
 	mutex_lock(&bsg_mutex);
@@ -943,7 +921,7 @@ static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 		if (copy_from_user(&hdr, uarg, sizeof(hdr)))
 			return -EFAULT;
 
-		rq = bsg_map_hdr(bd, &hdr);
+		rq = bsg_map_hdr(bd, &hdr, file->f_mode & FMODE_WRITE);
 		if (IS_ERR(rq))
 			return PTR_ERR(rq);